667
FXUS02 KWBC 101854
PMDEPD
EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
254 PM EDT MON OCT 10 2022
VALID 12Z THU OCT 13 2022 - 12Z MON OCT 17 2022
...HEAVY RAIN AND GUSTY WINDS ARE LIKELY THURSDAY-FRIDAY IN THE
NORTHEAST AHEAD OF A STRONG COLD FRONT...
..PATTERN OVERVIEW
A MORE ACTIVE FALL WEATHER PATTERN IS EXPECTED TO EVOLVE BY THE
END OF THIS WEEK AND CONTINUING INTO THE WEEKEND AS A COUPLE OF
COLD FRONTS ASSOCIATED WITH AN EASTERN U.S. AMPLIFYING UPPER LEVEL
TROUGH (AND EMBEDDED SHORTWAVES) MOVE ACROSS THE CENTRAL AND
EASTERN STATES. THE FIRST COLD FRONT WILL BE CROSSING THE
APPALACHIANS BY EARLY THURSDAY WITH WIDESPREAD SHOWERS AND STORMS
LIKELY AHEAD OF IT ACROSS THE EAST COAST REGION AND HEAVY RAIN AND
WIND FOR PORTIONS OF THE NORTHEAST. BY THIS WEEKEND, A SECOND COLD
FRONT DROPPING SOUTHWARD FROM CANADA IS EXPECTED TO REINFORCE THE
COOL AIRMASS ACROSS THE EASTERN HALF OF THE NATION. THE OPPOSITE
IS EXPECTED TO BE THE CASE ACROSS THE WEST COAST REGION AS AN
UPPER RIDGE BRINGS A PERIOD OF MUCH ABOVE NORMAL TEMPERATURES FROM
CALIFORNIA TO THE PACIFIC NORTHWEST.
..MODEL AND PREDICTABILITY ASSESSMENT
SYNOPTICALLY, THE LATEST SUITE OF 00Z/06Z MODEL GUIDANCE SHOWS
VERY GOOD AGREEMENT ALL THE WAY THROUGH DAY 7 ON THE OVERALL
PATTERN WHICH SHOWS AMPLIFIED TROUGHING OVER THE EASTERN U.S., AN
AMPLIFIED RIDGE OVER THE NORTHWEST, AND A VERY SLOW MOVING UPPER
LOW OFF THE SOUTHERN CALIFORNIA COAST WHICH MAY SLOWLY DRIFT
INLAND OVER THE SOUTHWEST BY EARLY NEXT WEEK. THE MAIN DIFFERENCES
DURING THE PERIOD LIE IN HANDLING OF INDIVIDUAL SMALLER SCALE
SHORTWAVES EMBEDDED WITHIN THE LARGER TROUGH, LEADING TO SOME
TIMING DIFFERENCES WITH ASSOCIATED COLD FRONTS. BY NEXT MONDAY/DAY
7, THERE IS ALSO UNCERTAINTY ON WHETHER AN UPPER LOW WILL CLOSE
OFF OVER THE UPPER GREAT LAKES OR REMAIN WELL TO THE NORTH/AN OPEN
TROUGH. THERE WAS ENOUGH RUN TO RUN VARIABILITY WITH THIS FEATURE
TO REQUIRE USE OF MODEST AMOUNTS OF THE ENSEMBLE MEAN SOLUTIONS BY
DAY 6 AND 7, IN ADDITION TO DETERMINISTIC SOLUTIONS AS WELL.
OVERALL THOUGH, THIS STILL MAINTAINS VERY GOOD CONSISTENCY WITH
THE PREVIOUS WPC FORECAST. FOR QPF, MAJOR CHANGES TO THE STARTING
POINT NBM MAINLY INVOLVED INCREASING AMOUNTS ACROSS THE GREAT
LAKES EARLY IN THE PERIOD, AND THEN ALSO AN INCREASE IN THE
COVERAGE AND AMOUNTS OF QPF ACROSS THE SOUTHERN PLAINS TO MIDWEST
AHEAD OF THE COLD FRONT.
..SENSIBLE WEATHER AND POTENTIAL HAZARDS
THE FIRST STRONG COLD FRONT AND THE ASSOCIATED UPPER TROUGH WILL
BRING A RETURN TO WIDESPREAD SHOWERS AND STORMS FROM THE
MID-ATLANTIC TO THE NORTHEAST ON THURSDAY. RAINFALL AMOUNTS ARE
LIKELY TO BE HIGHEST IN THE INTERIOR NORTHEAST THURSDAY AND
CONTINUING INTO FRIDAY ACROSS MAINE AS DEEPER ATLANTIC MOISTURE IS
ADVECTED TOWARDS THE NORTHERN APPALACHIANS WITH AN INCREASING LOW
LEVEL JET AND ANOMALOUSLY HIGH PWS. A SLIGHT RISK AREA REMAINS IN
PLACE IN WPC'S EXPERIMENTAL DAY 4 EXCESSIVE RAINFALL OUTLOOK FOR
THIS REGION. TERRAIN COULD ENHANCE RAIN TOTALS ACROSS THE
ADIRONDACKS AND THE WHITE AND GREEN MOUNTAINS, BUT LOWER
ELEVATIONS COULD SEE HEAVY RAINFALL AS WELL WITH A BROAD RISK FOR
SOME FLOODING. IF THE HEAVIER RAINFALL RATES ARE MORE LIMITED,
THEN THE FLOODING POTENTIAL SHOULD BE MITIGATED SOME. STRONG AND
GUSTY WINDS ARE ALSO A CONCERN THERE AS THE TROUGH BECOMES
NEGATIVELY TILTED AND THE PRESSURE GRADIENT TIGHTENS. ELSEWHERE,
LAKE ENHANCED RAIN AND SNOW SHOWERS ARE LIKELY ACROSS THE GREAT
LAKES FOR THE THURSDAY THROUGH SATURDAY TIME PERIOD, AND SHOWERS
COULD BECOME MORE WIDESPREAD WITH ANOTHER FRONTAL SYSTEM BY
SUNDAY. MOST OF THE WEST SHOULD REMAIN DRY THROUGH THE LATTER PART
OF THE WEEK WITH PERHAPS A FEW ISOLATED SHOWERS/STORMS OVER
ARIZONA AND NEW MEXICO INTO TEXAS, WITH COVERAGE LIKELY INCREASING
NEXT WEEKEND AS THE UPPER LOW SLOWLY MOVES INLAND OVER THE DESERT
SOUTHWEST.
MUCH OF THE NORTHWESTERN U.S. AND CALIFORNIA SHOULD HAVE ABOVE
NORMAL TEMPERATURES EACH DAY WITH THE UPPER RIDGE REMAINING NEARLY
ANCHORED IN PLACE NEAR THE COAST. ALTHOUGH, DAYTIME HIGHS COULD BE
10-15 DEGREES ABOVE NORMAL, THE RESULTING ACTUAL TEMPERATURES IN
THE 80S (NORTH) TO 90S (CALIFORNIA) SHOULD NOT PRESENT A HEAT
HAZARD. THE OPPOSITE WILL HOLD TRUE ACROSS THE NORTH-CENTRAL U.S.
AND EXTENDING TO THE EAST COAST, WITH HIGHS ABOUT 5-15 DEGREES
BELOW AVERAGE TO CLOSE OUT THE WORKWEEK AND GOING INTO NEXT
WEEKEND, WITH HIGHS ONLY IN THE 40S AND 50S FROM THE GREAT LAKES
TO THE NORTHEAST ON MOST DAYS.
SANTORELLI/HAMRICK
ADDITIONAL 3-7 DAY HAZARD INFORMATION CAN BE FOUND ON THE WPC
MEDIUM RANGE HAZARDS OUTLOOK CHART AT:
HTTPS://WWW.WPC.NCEP.NOAA.GOV/THREATS/THREATS.PHP
WPC MEDIUM RANGE 500MB HEIGHTS, SURFACE SYSTEMS, WEATHER GRIDS,
QUANTITATIVE PRECIPITATION, EXPERIMENTAL EXCESSIVE RAINFALL
OUTLOOK, WINTER WEATHER OUTLOOK PROBABILITIES AND HEAT INDICES ARE
AT:
HTTPS://WWW.WPC.NCEP.NOAA.GOV/MEDR/5DAYFCST500_WBG.GIF
HTTPS://WWW.WPC.NCEP.NOAA.GOV/MEDR/5DAYFCST_WBG_CONUS.GIF
HTTPS://WWW.WPC.NCEP.NOAA.GOV/5KM_GRIDS/5KM_GRIDSBODY.HTML
HTTPS://WWW.WPC.NCEP.NOAA.GOV/QPF/DAY4-7.SHTML
HTTPS://WWW.WPC.NCEP.NOAA.GOV/#PAGE=ERO
HTTPS://WWW.WPC.NCEP.NOAA.GOV/WWD/PWPF_D47/PWPF_MEDR.PHP?DAY=4
HTTPS://WWW.WPC.NCEP.NOAA.GOV/HEAT_INDEX.SHTML
CLICK HERE TO GO TO PREVIOUS BULLETINS.
Main Text Page